Sonic processing transducer



Sept. 2, 1969 F. MASSA SONIC PROCESSING TRANSDUCER 2 Sheets-Sheet 1Filed Oct. 26, 1966 wmufff f 4 u. RA 11C f m V Kv MM R,

Sept. 2, 1969 F. MASSA 3,464,672

SONIC PROCESSING TRANSDUCER Filed Oct. 26, 1966 2 Sheets-Sheet 2 FRANKMASS/1 INVENTOR.

United States Patent O 3,464,672 SONIC PROCESSING TRANSDUCER FrankMassa, Cohasset, Mass., assignor to Massa Division, Dynamics Corporationof America, Hingham, Mass.

Filed Oct. 26, 1966, Ser. No. 589,665 Int. Cl. B01f 11/02; B28c 5/08 US.Cl. 259-1 22 Claims ABSTRACT OF THE DISCLOSURE The invention provides asonic processing system having several embodiments. An especially usefulfeature common to all embodiments is the use of one or more cylindricalpiezoelectric transducers bonded to the inside or outside of a pliabletubular housing. This way, the flexibility of the pliable housingcompensates for any manufacturing variations, thus eliminating the needfor final machining to size and allowing for the use of widemanufacturing tolerances. The various embodiments feature discretecontainers for batch processing and tubular containers for continuousprocessing.

This invention relates to sonic processing transducers which generatevibrations by the radial oscillation of cylindrical shells and moreparticularly with an economical high power sonic processing systemcontaining polarized, ceramic tubular shell transducers made frommaterials such as lead zirconate titanate. Although this invention isparticularly advantageous for cylindrical or tubular ceramic shelltransducers because it nullifies the adverse effects of out-of-roundnessdeviations that occur in manufacturing ceramic cylinders or tubes andavoids the necessity for expensive grinding of fired elements, it isequally applicable to magnetostrictive vibrators.

A primary object of this invention is to provide an economical,cylindrical, sonic processing transducer in which radially vibratingcylindrical shells are bonded to the surface of a flexible, rubber-like,cylindrical tube; the pliable tubing being capable of deformation sothat any irregularities in the contour of the transducer shells will becompensated for by the pliable wall.

Another object of this invention is to provide an efficient, low cost,sonic processing system in which a cupshaped container is excited byradial vibrations through its cylindrical surface so that concentratedsonic energy is produced within a liquid that may be placed inside thecontainer.

A still further object of this invention is to provide a continuous,flexible tubular transducer assembly in which sonic vibrations aretransmitted through the wall of a flexible tube by means of cylindricalor tubular ceramic shell transducer elements bonded to the periphery ofthe flexible tube.

Another object of this invention is to provide a flexible, tubular sonicprocessing transducer through which a fluid may be transmitted forcontinuous, sonic processing.

Another object of this invention is to provide a composite, flexible,hose-like structure having an inner chamher through which a fluid may betransmitted for sonic processing and in which the hose-like transducerincludes an outer protective surface which is spaced from the tubulartransducer elements which are bonded to the outer periphery of the innertube.

A further object of the invention is to provide means for circulating afluid coolant through the space between the ceramic elements and theouter jacket for dissipating heat generated during high power operation.

A still further object of this invention is to provide a flexiblehose-like, sonic transducer suitable for continuous sonic processing ofa liquid which is passed through a 3,464,672- Patented Sept. 2, 1969concentric annular chamber between an outer pliable tube and an innerconcentric pliable tube wherein the transducer comprises tubular ceramicshells which are bonded to the inner periphery of the inside concentrictube and capable of being excited in a radial mode of vibration.

An additional object of this invention is to provide means forcontinuous sonic processing of a fluid by passing the fluid through arelatively long hose-like structure into which sonic vibrations aretransmitted by a plurality of radially vibrating tubular shells attachedto the peripheral wall of the hose-like structure.

The novel features which are characteristic of this invention are setforth with particularity in the appended claims; however, theorganization, method of operation, and advantages of the invention willbe understood best from the following description of several embodimentsillustrated in the accompanying drawings in which:

FIGURE 1 is a vertical cross-sectional view of a transducer constructedaccording to this invention containing a flexible, tubular cup-likecontainer mounted at the top of a cylindrically shaped, plastic housing,a single ceramic ring transducer element mounted on the container, andan electronic power supply for energizing the transducer;

FIGURE 2 is a partial vertical section illustrating a modification ofthe transducer of FIGURE 1 containing a deeper flexible cylindricalcontainer and three ceramic ring transducer elements bonded to theperiphery of the tank for increasing the capacity of the sonicprocessing unit; 7

FIGURE 3 is an axial sectional view of a long tubular sonic processingtransducer embodying another form of the invention;

FIGURE 4 is a view taken along the section line 4-4 of FIGURE 3.

FIGURE 5 is an axial sectional view showing a modified form of thisinvention incorporated in a tubular transducer in which sonic vibrationsare generated in the annular space between two concentric tubularelements;

FIGURE 6 is a view taken along the section line 66 of FIGURE 5;

FIGURE 7 illustrates a continuous sonic processing installation makinguse of a long section of a coiled tubular transducer constructedaccording to this invention; and

FIGURE 8 illustrates another application of a tubular sonic processingtransducer of this invention in which a batch of liquid may becirculated through the transducer for an extended period of time.

Referring more particularly to the figures in which the same referencecharacters will be used to identify similar elements, FIGURE 1illustrates a portable sonic processing unit incorporating a cylindricalor tubular container 10 which may be made of a molded, rubber-likesubstance for holding the material to be sonically processed. To theouter surface of the container 10, is bonded a tubular transducerelement 12 which may comprise a polarized, piezoelectric ceramic ring ofa material such as barium titanate, lead zirconate titanate, or anyother similar material which is capable of being excited into radialvibration, sometimes referred to in the art as the circumferential modeof vibration, by the application of an alternating voltage to itselectrodes such as the electrodes 14 and 16.

In the illustrated example, the ceramic element 12 is provided with anouter cylindrical electrode 16 and an inner cylindrical electrode 14.These electrodes are used for polarizing the ceramic element during itsmanufacture in the conventional manner. The inner surface of the ceramicring 12 is bonded to the outer wall of the container 10 by a suitablelayer of cement 18'which may be an epoxy film or other suitableadhesive.

Of special importance in the economical manufacture of the transducerassembly is the fact that the container is pliable and has outer wallswhich may be deformed easily to fit the exact contour of the ceramicring 12. Because of this, the ceramic rings need not 'be ground toprecise dimensions to achieve a secure mechanical contact through thecement layer 18.

A further advantage of using a rubber-like material, such aspolybutadiene, for forming the cup is that the container 10 remainsremarkably free of defects which are caused by cavitation at thecontainer surfaces during operation. Such a transducer is more durablethan one comprising a metal cup.

To achieve a reliable bond between the outer wall of container 10 andthe inner surface of the ceramic ring 12, a tool, such as a thick rubbercylinder which may be placed within the opening of the container 10 andsqueezed by means such as a mechanical clamp so that outward radialpressure is exerted on the inside wall of the container 10 to deform thewall into the exact contour of the inner surface of the ceramic ring 12,may be used. When the bonding is completed, the pressure tool is removed and perfect acoustical coupling is achieved at low cost withoutmachining the inside surface of the ceramic cylinder. Prior to bondingthe ceramic element 12 to the wall of container 10, electricalconductors 20 and 22 are soldered respectively to the electrode surfaces14 and 16.

If desired, the fundamental advantages of this invention can be securedwith other transducer elements such as a laminated, magnetostrictivemetal alloy shell, of a material such as nickel, having a suitabletoroidal excitation winding.

The combination of the ceramic tube or ring 12 and the pliable container10 forms the basic transducer structure. FIGURE 1 illustrates how thetransducer assembly may be combined with a housing and electronic powersupply to form a complete sonic processing unit which is portable.

The container 10 may be molded with a flange-like periphery 26 which maybe sealed to the open end of a housing such as molded plastic cylinder28. Near the opposite internal opening of the housing 28, several bosses30 may be placed to serve as mounting surfaces. A base plate 32 may befastened to the bosses 30 by screws. The base plate 32 supportselectronic oscillator and power supply 34, which may compriseconventional circuitry.

The conductors 20 and 22 are connected to output terminals 36 and 38 ofthe power supply 34. A power cord 40, which may be supported by agrommet 4'4 molded near its end has two insulated conductors 46 and 48which are soldered to the terminals 52 and 54 of the power supply 34.Near the bottom open end of the housing 28, a closure plate 60 may befastened to bosses 62 by means of the screws to complete the assembly ofthe transducer. Molded rubber feet 66 may be inserted in the peripheryof closure plate 60, as illustrated, to serve as a support.

When the electrical power supply is activated and the ceramic ring 12 isdriven at its radial mode resonant frequency, intense sonic energy willbe transmitted into liquid 70 within container 10.

FIGURE 2 illustrates a modification of the transducer of FIGURE 1 inwhich the tubular container 10 is made deeper. Instead of a single ring,several polarized ceramic rings 12 are bonded to the wall of container10 described in connection with FIGURE 1. The inside electrodes 14 ofthe rings 12 are interconnected by conductors 80. The outside electrodes16 of the rings are connected by means of the conductors 82. Theparallel connected ceramic elements 12 are connected to an electronicpower supply (not shown) by conductors 20 and 22.

Except for the deeper container 10 and the use of multiple transducerelements 12, the construction of the transducer of FIGURE 2 is identicalto that of FIG- URE 1.

It is advantageous to make the axial width of the ceramic rings 12 lessthan the largest radial dimension,

the largest dimension in the direction orthogonal to the axis of thetube such as the diameter of the rings where circular rings are used,because in relatively wide rings, the radial resonant mode of vibrationof the rings is aifected by the longitudinal resonant mode of vibration.

FIGURES 3 and 4 illustrate a section of a tubular conduit whichincorporates another form of a transducer of this invention which isuseful for the continuous sonic processing of liquids. In thisembodiment a long (measured in feet) flexible tube 90, which may be madeof a rubber-like material such as polybutadiene which resists cavitationdeterioration, has a number of ceramic rings 12 bonded to its outersurface in a manner similar to that which was described previously. Theelectrodes 14 on the inner surface of the ceramic rings 12 are connectedtogether by flexible conductors prior to the bonding of the electrodesurfaces to the outer periphery of the flexible tube by'the cementlayer.

An inexpensive method of bonding a number of elements to the outersurface of the tube 90 comprises pumping air into the opening of thetube 90 to cause the flexible walls to expand and to make completecontact to the inner surfaces of the rings 12. The outer wall of thetube 90 conforms to the various irregularities and deviations that occurin the inner peripheral dimensions of the ceramic rings 12. The tube 90is pressurized until the cement 18 is completely cured.

After completing the bonding of the ceramic rings 12 to the tube 90, theouter electrodes 16 are connected in parallel by the flexible leads 82as illustrated.

The external housing of the assembly comprises a flexible, extruded tube92 having a number of internal spacing ribs 94 for supporting the tube92 in generally concentric relation around tube 90 as shown in FIGURE 3.When the tube 92 is assembled as an outer jacket over the outsideperiphery of the rings 12, an annular space or chamber remains betweenthe inner wall of the tube 92 and the outer surfaces of the ceramicrings 12. This annular space forms a continuous air duct along thelength of the transducer assembly through which air or another fluid canbe supplied to cool the transducer during high power operation or toregulate the temperature of the fluid being processed.

The liquid to be sonically processed is pumped through the tube 90. Whenthe ceramic rings 12 are electrically energized, sonic vibrationsgenerated by the rings are transmitted directly to the liquid within thetube 90.

Because the tubes 90 and 92 are flexible and the ceramic rings 12 arespaced apart and connected by flexible leads, the tubular transducer canbe bent, twisted or coiled as operating conditions require, therebyfacilitating the storage of long lengths of the tubular transducer inrelatively small and confined spaces.

A variation of the flexible tubular transducer described in FIGURES 3and 4 is illustrated in FIGURES 5 and 6. In this embodiment, the innerwall surface of a flexible tube is bonded to the outer peripheries ofthe electrodes 14 and outer electrodes 16 are connected respectively inparallel by electric conductors 80 and 82. After the assembled group ofcement coated ceramic rings 12 are placed inside the cement coated tube100, radical pressure is exerted against the outer surface of flexibletube 100 to insure bonding between the rings 12 and the tube 100. Theradial pressure may be applied by any number of methods such as thewrapping of the tube 100 with rubber tape stretched over its outersurface. An outer, flexible extruded tube 102, which may have internalspacing ribs 104, surrounds the tube 100 and serves as the housing ofthe sonic processing transducer. Because of the presence of the ribs104, a peripheral chamber 106 is provided through which a liquid may bepassed for sonic processing. Center chamher 110 which passes through therings 12 may be used as a duct for a fluid which regulates thetransducer temperature so that the optimum processing temperature may bemaintained.

The basic function of both the transducer structures described inFIGURES 3 and 4 and FIGURES 5 and 6 is the same; namely, the sonicprocessing of liquids during their passage through a long continuousduct. The transducer illustrated in FIGURES 3 and 4 concentrates energyinto a central chamber, whereas the embodiment illustrated in FIGURES 5and 6 distributes sonic energy in a peripheral chamber which, for agiven size of transducer ring 12, provides a greater cross-sectionalarea of chamber for sonic processing than can be obtained with atransducer having a central processing chamber. The structure shown inFIGURES 5 and 6 may be preferred for certain types of industrialprocessing in which high rates of fluid flow are desired within atransducer of a minimum size.

For reasons previously described, optimal performance is achieved whenthe width of the ceramic rings 12 does not exceed the largest radialdimension, such as the diameter of the rings. This limitation isimportant for another reason; namely, a more flexible tube is obtainablewith narrow rings than would be the case if wide rings were used.

The tubular transducers may be made in standard, modular lengths andprovided with suitable end connections to permit coupling of any numberof modules together to produce a total length of flexible transducer ofany desired dimension. It is further possible to design each modularlength of transducer so that it is operated by a separate electronicpower supply; thereby increasing the reliability of the complete sonicprocessing system by providing redundancy.

FIGURE 7 illustrates one embodiment of the invention combined in acontinuous sonic processing system. Container 120 serves as a reservoirfor the product which is to be sonically activated. A helically coiledlength of tubular transducer 122 is fabricated from a number of modulesof tubular transducer sections, as described above in FIGURES 3-6. Thetotal length of the coiled transducer 122 is determined by the rate offlow of the liquid to be processed and the amount of time that thematerial is to be exposed to the sonic vibration. A valve 124 having 'anoutlet 126 is connected to the free end of the transducer 122.

To use the continuous sonic processing system shown in FIGURE 7, theingredients to be processed are poured into the container 120 and thevalve is adjusted to regulate the desired rate of flow through thecoiled transducer. During the flow of the material through the tubulartransducer, the transducer elements are energized by their powersupplies to cause continuous sonic processing of the material flowingthrough the coiled transducer 122.

A batch processing system incorporating a tubular transducer isillustrated in FIGURE 8. A suitable container 130 is provided forholding a quantity of material which is to be sonically processed. Alength of tubular transducer comprising sections 134 and 136 isconnected between a drain tube 140 located near the bottom of the tankand a fill tube 142 located near the top of the tank. A pump 144 isconnected in series with the tubular transducer sections 134 and 136.The pump .144 circulates the liquid 132 through the system so that itwill be continuously passed through the loop formed by the tubulartransducer for whatever period of time is required to achieve thedesired results from the sonic processing.

While there have been shown and described several specific illustrativeembodiments of the present invention, it will, of course, be understoodthat various modifications and alternative constructions may be madewithout departing from the true spirit and scope of the invention.Therefore the appended claims are intended to cover all suchmodifications and alternative constructions as fall within their truespirit and scope.

What is claimed is:

1. A sonic processing appliance comprising a transducer element capableof vibrational excitation in a circumferential mode, said transducerhaving a generally tubular shape with inner and outer peripheral walls,a container having a flexible tubular wall, the outer peripheral wall ofsaid flexible container having approximately the same peripheraldimensions as the inner pe ripheral wall of said tubular transducerelement, and means for bonding said inner Wall surface of said transducer element to said outer wall surface of said flexible tubularcontainer.

2. The sonic processing appliance of claim 1 wherein the transducerelement is a piezoelectric transducer element.

3. The sonic processing appliance of claim 1 wherein the transducerelement is a magnetostrictive transducer element.

4. The sonic processing appliance of claim 1 wherein said transducerelement is a cylindrical shell, and wherein the axial length of theshell does not exceed the outside diameter of the shell.

5. The sonic processing appliance of claim 1 comprising in addition: arigid housing having an open end; and a flange secured to the open endof the housing; and wherein the tubular container is supported at oneend by the flange and the other end of the tubular container is sealedto form a cup.

6. The sonic processing appliance of claim 5 wherein the flange and thetubular container are of an integral, seamless construction.

7. The sonic processing appliance of claim 5 comprising in addition:means, secured to the interior of the housing, for energizing thetransducer elements.

8. A sonic processing appliance comprising a rigid walled housing havingan open end, a flexible walled cylindrical cup-shaped container havingan extended flange portion at its open end, said extended flange portionbeing shaped for mounting upon and forming a closure over the open endof said rigid housing, a plurality of transducer elements each having acylindrical tubular shape capable of vibrational excitation in acircumferential mode, each transducer having inner and outer peripheralwalls, and means for bonding the inner peripheral walls of each of saidplurality of transducer elements to the outer peripheral wall of saidflexible cupshaped container.

9. The appliance of claim 8 wherein the axial length of each of saidcylindrical transducer elements does not exceed the outer diameters ofsaid cylindrical elements.

10. The appliance of claim 8 comprising in addition: means, secured tothe inside of the housing, for energizing the transducer elements.

11. A sonic processing transducer comprising a flexible tubular conduithaving an inner and outer wall surface, a plurality of transducerelements, each of said elements having a tubular shape with inner andouter wall surfaces, and means for bonding the inner wall surfaces ofeach of said plurality of said transducer elements to the outer wallsurface of said flexible tubular conduit.

12. The invention set forth in claim 11 wherein both said tubularconduit and said tubular transducer elements are cylindrical in shape,the axial length of said transducer elements being less than the outerdiameter of said elements.

13. The sonic processing transducer of claim 12 comprising in addition:a second flexible tubular conduit having an inner diameter which isgreater than the outer diameters of the transducer elements, said secondconduit forming an enclosed housing around the transducer elements; andmeans for supporting the second tubular conduit in generally concentricrelation with the first tubular conduit.

14. The sonic processing transducer of claim 13 wherein a chamber isformed between the first and second tubular conduits.

15. A sonic processing transducer comprising first and second flexibletubular conduits, each of said conduits having inner and outercylindrical wall surfaces, a plurality of cylindrical transducerelements, each of said elements having inner and outer wall surfaces,means for bonding the outer surfaces of said transducer elements to theinner wall of a first of said flexible tubular conduits, the second ofsaid cylindrical tubular conduits coaxially surrounding said firsttubular conduit, and longitudinal spacing means between the outersurface of said first conduit and the inner surface of said secondconduit whereby an annular duct is provided between said first andsecond conduits.

16. The sonic processing transducer of claim 15 wherein the axial lengthof each transducer element is less than its outside diameter.

17. A continuous sonic processing system comprising:

(a) a tubular sonic transducer containing (i) a flexible wall defining achamber through which fluid to be sonically processed may flow, and

(ii) cylindrical transducer means bonded to said flexible wall fortransmitting sonic vibrations through the wall into the chamber; and

(b) means for circulating the fluid through the chamber at a controlledrate of flow.

18. The continuous sonic processing system of claim 17 comprising inaddition:

a container in fluid communication with the tubular sonic transducer,for holding the fluid to be processed; and wherein the tubular sonictransducer is coiled.

19. The continuous sonic processing system of claim 17 comprising inaddition:

a container, for holding the fluid to be processed, having a fill tubefor filling the container with fluid and a drain tube for draining thecontainer of fluid; and wherein one end of the tubular sonic processingtransducer is connected to the fill tube and the other end of thetubular sonic processing transducer is connected to the drain tube. 20.A sonic processing transducer comprising: (a) a tubular, rigid-walledhousing having an open end and a closed end, the closed end forming abase for supporting the housing in a position such that its axis isgenerally perpendicular to the plane of a surface supporting thetransducer;

(b) a cup-shaped container of pliable material, the container having aperipheral wall portion generally parallel with the axis of thecup-shaped container and an extended flange portion located at the openend of the container, the plane of the flange being generally transverseto the axis of the container;

(c) means for securing the flange to the open end of the housing to forma cover for the housing and to support the container within the housing;

(d) a tubular transducer element, capable of vibration in a radial mode,having an inner wall and an outer wall;

(e) means for bonding the inner wall of the transducer element to theouter surface of the peripheral wall portion of the container; and

(f) means, secured to the inside of the housing, for energizing thetransducer element.

21. The sonic processing transducer of claim 20 wherethe transducerelement is a polarized, ceramic shell of piezoelectric material.

22. The sonic processing transducer of claim 20 comprising:

a plurality of tubular transducer elements capable of vibration in aradial mode, the elements being bonded at their inner walls to the outersurface of the peripheral wall portion of the container.

References Cited UNITED STATES PATENTS 2,407,462 9/1946 Whiteley.2,578,505 12/1951 Carlin. 2,585,103 2/1952 Fitzgerald. 3,021,120 2/1962Van der Burgt. 3,056,589 10/ 1962 Daniel. 3,165,299 1/ 1965 Balamuth et21. 3,180,626 4/1965 Mettler 2591 XR 3,194,640 7/1965 Nesh 259-1 XR3,195,586 7/1965 Vogt 2594 XR WALTER A. SCHEEL, Primary Examiner JOHN M.BELL, Assistant Examiner US. Cl. X.R. 2592, 4, 72

